It is an object of the present invention to provide amedicament for preventing or treating hyperphosphatemia.Solution: A compound having general formula (I) or apharmaceutically acceptable salt thereof.(see formula I)wherein:R1 is a C1-6 alkyl group, a C1-6 alkoxy C1-6 alkyl group, aC3-6 cycloalkyl group, or a C3-6 cycloalkyl C1-6 alkyl group；R2 is a hydrogen atom or a halogen group； R3 is a hydrogenatom, a halogen group, a halogeno C1-6 alkyl group, a halogenoC1-6 alkoxy group, a C2-5 saturated cyclic amino group, a C1-6dialkylamino group, a C3-6 cycloalkyl C1-6 alkoxy group or aC1-6 alkoxy group； A is a C3-6 cycloalkyl ring； X is CH or N；Y is CH or N； Z is CH or N； and n is 1, 2, 3 or 4.
